【作者】 万大娟；

【导师】 张杨珠；

【作者基本信息】 湖南农业大学 ， 土壤学， 2003， 硕士

【摘要】 本文通过野外调查取样、室内培养试验和分析测定，研究了湖南省主要旱耕地土壤的固定态铵含量、固铵容量、有效性固定态铵含量以及土壤对铵离子的矿物固定和土壤固定态铵释放的动力学特性，通过田间小区试验，研究了不同施肥结构下土壤固定态铵在黄花菜生长期间的动态变化规律及其生物有效性。主要研究结果如下： 1．供试耕层土壤固定态铵含量及其占全氮含量百分数分别在59.4～435.7mg·kg^-1和4.6～60.1％范围内变化。一般情况下，土壤剖面中的固定态铵含量在0～40cm范围内变化不大，40cm以下升高或无明显变化；它占土壤全氮含量百分数则是随剖面深度增大而增大。其影响因素主要有成土母质、粘土矿物组成、土壤pH值、＜0.01mm粘粒含量和阳离子交换量等。 2．供试耕层土壤和剖面土壤的固铵容量分别在3.3～203.3mg·kg^-1和3.6～242.2mg·kg^-1范围内变化，最大固铵容量分别在80.9～533.9mg·kg^-1和60.6～574.7mg·kg^-1范围内变化。其影响因素主要有成土母质、粘土矿物组成、土壤阳离子交换量、pH值、有机质含量、碱解氮含量和土壤溶液中铵离子浓度等。 3．供试土壤对外源铵离子的累计固定量随时间的延长而迅速增加，反应以开始阶段固定速率最大，由同种母质发育的酸碱度不同的土壤对铵离子的固定能力不同。供试土壤固定态铵的累计释放量随着时间的延长而缓慢增加，反应42天仍未达到最大值，土壤溶液中阳离子种类能影响固定态铵的释放。一级动力学方程和抛物扩散率方程均适合于拟合土壤对铵离子矿物固定和固定态铵释放的动力学资料。 4．供试土壤中“原有”和“新固定”的固定态铵分别有0.0～17.4％和54.1～100.0％可释放出来，“新固定”固定态铵的有效性远远大于“原有”固定态铵。在黄花菜生育期间，土壤固定态铵与碱解氮的动态变化基本一致。黄花菜吸氮量和生物产量与土壤总氮素供应量呈显著的正相关关系。更多还原

【Abstract】 The content of fixed ammonium, capacity of fixing-ammonium, available fixed ammonium, kinetics of ammonium fixation and release of fixed ammonium of chief upland cultivated soils in Hunan Province were studied by using the method of field investigation and sampling, laboratory incubation and analyses. The seasonal change of fixed ammonium content in soil and_ its bioavailability in different growth stage of Huanghuacai by use of field plot experiment. The main results were as follows:1. The content of fixed ammonium of cultivated horizon in soils tested ranged from 59.4 to 435.7 mg-kg-1, the percentage of fixed ammonium to total N ranged from 4.6 to 60.1%. In the profile of 0~40 centimeter depth, the content of fixed ammoniumhad no distinct change, and it increased or had no distinct change in the profile of 40~75 centimeter depth. The percentage of fixed ammonium to total N in soils steadily increased with the increasing of depth. The soil factors affecting fixed ammonium content in soils tested were mainly parent material, soil clay composition, pH, CEC and the content of clay (<0.01mni) .2. The capacity and maximum capacity of fixing-ammonium in the cultivated horizon ranged from 3.3mg-kg-1 to 203.3 mg-kg-1 and 80.9mg-kg-1 to 533.9 mg-kg-1, respectively. And that in soil profiles tested ranged from 3.6mg-kg-1 to 242.2mg-kg-1 and 60.6mg-kg-1 to 574.7 mg-kg-1, respectively. The soil factors affecting the capacity of fixing-ammonium in tested soils were mainly parent material, soil clay composition, pH, CEC, organic matter, available N and concentration of NH4+ in soil.3.The fixing quantity of ammonium in soils tested increased with the increasing of the fixation time, and the fixation rate was the largest at the beginning several hours. The releasing amount of fixed NH/ in soils tested increased with the incubation time, and the velocity of fixed-NH4+-release was very slow. The release of fixed ammonium still continued at the reaction time of 42 days. pH was an affecting factor of NH4+-fixation in soil and the category of cation was an affecting factor of fixed-NH4+-release from soil. Both first-order equation and parabolic diffusion law equation were the most adaptable to describe the NH4+-fixation and fixed-NH4+-release kinetics. 4.0.0 ~ 17.4% of inherently fixed ammonium and 54.1 ~ 100.0% of recently fixedammonium in soils tested released during the incubation time. The availability ofrecently fixed ammonium was far higher than inherently fixed ammonium. Change of the fixed ammonium content in soil in different growth stage of Huanghuacai was similar with available N content. The total N uptake and the biomass of Huanghuacai was positively correlated with the net release of soil N at the significant level of P0.05.更多还原